Coolant drip facilitating partial immersion-cooling of electronic components

ABSTRACT

Cooling apparatus and methods are provided for partial immersion-cooling of multiple electronic components. The cooling apparatus includes a housing at least partially surrounding and forming a compartment about the components, and a fluid disposed within the compartment. First and second electronic components are at least partially non-immersed within the fluid, with the first component being a different type of electronic component with different configuration than the second component. A vapor condenser is provided with a vapor-condensing surface disposed within the compartment for condensing fluid vapor, and a condensate redirect structure is disposed within the compartment between the vapor condenser and the first and second components. The redirect structure is differently configured over the first electronic component compared with over the second electronic component, and provides a different pattern of condensate drip over the first component compared with over the second component.

BACKGROUND

The power dissipation of integrated circuit chips, and the modulescontaining the chips, continues to increase in order to achieveincreases in processor performance. This trend poses cooling challengesat the module and system levels.

In many large server applications, processors along with theirassociated electronics (e.g., memory, disk drives, power supplies, etc.)are packaged in removable drawer configurations stacked within anelectronics rack or frame comprising information technology (IT)equipment. In other cases, the electronics may be in fixed locationswithin the rack or frame. Typically, the components are cooled by airmoving in parallel airflow paths, usually front-to-back, impelled by oneor more air moving devices (e.g., fans or blowers). In some cases it maybe possible to handle increased power dissipation within a single draweror subsystem by providing greater airflow, for example, through the useof a more powerful air moving device or by increasing the rotationalspeed (i.e., RPMs) of an existing air moving device. However, thisapproach is becoming problematic, particularly in the context of acomputer center installation (i.e., data center).

The sensible heat load carried by the air exiting the rack is stressingthe capability of the room air-conditioning to effectively handle theload. This is especially true for large installations with “serverfarms” or large banks of computer racks located close together. In suchinstallations, liquid-cooling is an attractive technology to manage thehigher heat fluxes. The liquid absorbs the heat dissipated by thecomponents/modules in an efficient manner. Typically, the heat isultimately transferred from the liquid to an outside environment,whether air or other liquid.

BRIEF SUMMARY

The shortcomings of the prior art are overcome and additional advantagesare provided through the provision of a cooling apparatus comprising,for instance, a housing, a fluid, a vapor condenser, and a condensateredirect structure. The housing is configured to at least partiallysurround and form a compartment about multiple electronic components tobe cooled. The fluid is disposed within the compartment, and a firstelectronic component of the multiple electronic components is at leastpartially non-immersed within the fluid, and a second electroniccomponent of the multiple electronic components is at least partiallynon-immersed within the fluid, wherein the first electronic componentand the second electronic component are different types of electroniccomponents with different configurations. The vapor condenser includes avapor-condensing surface disposed at least partially in a vapor regionof the compartment for condensing fluid vapor, and the condensateredirection structure is disposed within the compartment at leastpartially between the vapor condenser and the first and secondelectronic components. The condensate redirect structure is differentlyconfigured over the first electronic component compared with over thesecond electronic component, and provides a different pattern ofcondensate drip over the first electronic component compared with overthe second electronic component.

In another aspect, a liquid-cooled electronic system is provided whichincludes an electronic system comprising multiple electronic componentsto be cooled, and a cooling apparatus partially immersion-cooling theelectronic system. The cooling apparatus includes, for instance, ahousing, a fluid, a vapor condenser, and a condensate redirectstructure. The housing at least partially surrounds and forms acompartment about the multiple electronic components to be cooled. Thefluid is disposed within the compartment, and a first electroniccomponent of the multiple electronic components is at least partiallynon-immersed within the fluid, and a second electronic component of themultiple electronic components is at least partially non-immersed withinthe fluid, wherein the first electronic component and the secondelectronic component are different types of electronic components withdifferent configurations. The vapor condenser includes avapor-condensing surface disposed at least partially in a vapor regionof the compartment for condensing fluid vapor, and the condensateredirect structure is disposed within the compartment at least partiallybetween the vapor condenser and the first and second electroniccomponents. The condensate redirect structure is differently configuredover the first electronic component compared with over the secondelectronic component, and provides a different pattern of condensatedrip over the first electronic component compared with over the secondelectronic component.

In a further aspect, a method of facilitating cooling of an electronicsystem is provided. The method includes: providing a housing at leastpartially surrounding and forming a compartment about multipleelectronic components of the electronic system; providing a fluiddisposed within the compartment in contact with one or more electroniccomponents of the multiple electronic components within the compartment,wherein a first electronic component of the multiple electroniccomponents is at least partially non-immersed within the fluid, and asecond electronic component of the multiple electronic components is atleast partially non-immersed within the fluid, the first electroniccomponent and the second electronic component being different types ofelectronic components with different configurations; providing a vaporcondenser comprising a vapor-condensing surface disposed at leastpartially in a vapor region of the compartment for condensing fluidvapor; and disposing a condensate redirect structure within thecompartment at least partially between the vapor condenser and the firstand second electronic components, the condensate redirect structurebeing differently configured over the first electronic componentcompared with over the second electronic component, and providing adifferent pattern of condensate drip over the first electronic componentcompared with over the second electronic component.

Additional features and advantages are realized through the techniquesof the present invention. Other embodiments and aspects of the inventionare described in detail herein and are considered a part of the claimedinvention.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

One or more aspects of the present invention are particularly pointedout and distinctly claimed as examples in the claims at the conclusionof the specification. The foregoing and other objects, features, andadvantages of the invention are apparent from the following detaileddescription taken in conjunction with the accompanying drawings inwhich:

FIG. 1 depicts one embodiment of a conventional raised floor layout ofan air-cooled computer installation;

FIG. 2 is a front elevational view of one embodiment of a liquid-cooledelectronics rack comprising multiple electronic systems to be cooled viaa cooling apparatus, in accordance with one or more aspects of thepresent invention;

FIG. 3 is a schematic of an electronic system of an electronics rack andone approach to liquid-cooling of an electronic component with theelectronic system, wherein the electronic component is indirectlyliquid-cooled by system coolant provided by one or more modular coolingunits disposed within the electronics rack, in accordance with one ormore aspects of the present invention;

FIG. 4 is a schematic of one embodiment of a modular cooling unit for aliquid-cooled electronics rack such as illustrated in FIG. 2, inaccordance with one or more aspects of the present invention;

FIG. 5 is a plan view of one embodiment of an electronic system layoutillustrating an air and liquid-cooling approach for cooling electroniccomponents of the electronic system, in accordance with one or moreaspects of the present invention;

FIG. 6A is an elevational view of an alternate embodiment of aliquid-cooled electronics rack with immersion-cooling of electronicsystems thereof, in accordance with one or more aspects of the presentinvention;

FIG. 6B is a cross-sectional elevational view of one immersion-cooledelectronic system of the liquid-cooled electronics rack of FIG. 6A, inaccordance with one or more aspects of the present invention;

FIG. 7A is a cross-sectional elevational view of one embodiment of apartial immersion-cooled electronic system for, for example, aliquid-cooled electronics rack, in accordance with one or more aspectsof the present invention;

FIG. 7B is a plan view of one embodiment of a condensate redirectstructure of the partial immersion-cooled electronic system of FIG. 7A,in accordance with one or more aspects of the present invention;

FIG. 8A is a cross-sectional elevational view of an alternate embodimentof a partial immersion-cooled electronic system for, for example, aliquid-cooled electronics rack, in accordance with one or more aspectsof the present invention;

FIG. 8B is a plan view of one embodiment of a condensate redirectstructure of the partial immersion-cooled electronic system of FIG. 8A,in accordance with one or more aspects of the present invention;

FIG. 9A is a cross-sectional elevational view of another embodiment of apartial immersion-cooled electronic system for, for example, aliquid-cooled electronics rack, in accordance with one or more aspectsof the present invention;

FIG. 9B is a plan view of one embodiment of a condensate redirectstructure of the partial immersion-cooled electronic system of FIG. 9A,in accordance with one or more aspects of the present invention; and

FIG. 10 is an elevational view of one embodiment of a liquid-cooledelectronics rack with partial immersion-cooling of electronic systemsthereof, in accordance with one or more aspects of the presentinvention.

DETAILED DESCRIPTION

As used herein, the terms “electronics rack”, “rack-mounted electronicequipment”, and “rack unit” are used interchangeably, and unlessotherwise specified include any housing, frame, rack, compartment, bladeserver system, etc., having one or more heat-generating components of acomputer system, electronic system, or information technology equipment,and may be, for example, a stand alone computer processor having high-,mid- or low-end processing capability. In one embodiment, an electronicsrack may comprise a portion of an electronic system, a single electronicsystem, or multiple electronic systems, for example, in one or moresub-housings, blades, books, drawers, nodes, compartments, etc., havingone or more heat-generating electronic components disposed therein. Anelectronic system(s) within an electronics rack may be movable or fixed,relative to the electronics rack, with rack-mounted electronic drawersand blades of a blade center system being two examples of electronicsystems (or subsystems) of an electronics rack to be cooled.

“Electronic component” refers to any heat generating electroniccomponent of, for example, a computer system or other electronics unitrequiring cooling. By way of example, an electronic component maycomprise one or more integrated circuit dies and/or other electronicdevices to be cooled, including one or more processor dies, memory diesor memory support dies. As a further example, the electronic componentmay comprise one or more bare dies or one or more packaged dies disposedon a common carrier. Further, unless otherwise specified herein, theterms “liquid-cooled cold plate”, “liquid-cooled base plate”, or“liquid-cooled structure” each refer to any conventional thermallyconductive structure having a plurality of channels or passagewaysformed therein for flowing of liquid-coolant therethrough.

As used herein, a “liquid-to-liquid heat exchanger” may comprise, forexample, two or more coolant flow paths, formed of thermally conductivetubing (such as copper or other tubing) in thermal or mechanical contactwith each other. Size, configuration and construction of theliquid-to-liquid heat exchanger can vary without departing from thescope of the invention disclosed herein. Further, “data center” refersto a computer installation containing one or more electronics racks tobe cooled. As a specific example, a data center may include one or morerows of rack-mounted computing units, such as server units.

One example of facility coolant and system coolant is water. However,the concepts disclosed herein are readily adapted to use with othertypes of coolant on the facility side and/or on the system side. Forexample, one or more of these coolants may comprise a brine, adielectric liquid, a fluorocarbon liquid, a liquid metal, or othersimilar coolant, or a refrigerant, while still maintaining theadvantages and unique features of the present invention.

Reference is made below to the drawings, which are not drawn to scalefor ease of understanding of the various aspects of the presentinvention, wherein the same reference numbers used throughout differentfigures designate the same or similar components.

As shown in FIG. 1, in a raised floor layout of an air-cooled datacenter 100 typical in the prior art, multiple electronics racks 110 aredisposed in one or more rows. A computer installation such as depictedin FIG. 1 may house several hundred, or even several thousandmicroprocessors. In the arrangement of FIG. 1, chilled air enters thecomputer room via floor vents from a supply air plenum 145 definedbetween the raised floor 140 and a base or sub-floor 165 of the room.Cooled air is taken in through louvered covers at air inlet sides 120 ofthe electronics racks and expelled through the backs, i.e., air outletsides 130, of the electronics racks. Each electronics rack 110 may haveone or more air-moving devices (e.g., fans or blowers) to provide forcedinlet-to-outlet air flow to cool the electronic components within thedrawer(s) of the rack. The supply air plenum 145 provides conditionedand cooled air to the air-inlet sides of the electronics racks viaperforated floor tiles 160 disposed in a “cold” aisle of the computerinstallation. The conditioned and cooled air is supplied to plenum 145by one or more air conditioning units 150, also disposed within datacenter 100. Room air is taken into each air conditioning unit 150 nearan upper portion thereof. This room air may comprise (in part) exhaustedair from the “hot” aisles of the computer installation defined byopposing air outlet sides 130 of the electronics racks 110.

FIG. 2 depicts one embodiment of a liquid-cooled electronics rack 200comprising a cooling apparatus. In one embodiment, liquid-cooledelectronics rack 200 comprises a plurality of electronic systems 210,which may be processor or server nodes (in one embodiment). A bulk powerassembly 220 is disposed at an upper portion of liquid-cooledelectronics rack 200, and two modular cooling units (MCUs) 230 arepositioned in a lower portion of the liquid-cooled electronics rack forproviding system coolant to the electronic systems. In the embodimentsdescribed herein, the system coolant is assumed to be water or anaqueous-based solution, by way of example only.

In addition to MCUs 230, the cooling apparatus depicted includes asystem coolant supply manifold 231, a system coolant return manifold232, and manifold-to-node fluid connect hoses 233 coupling systemcoolant supply manifold 231 to electronic subsystems 210 (for example,to cold plates or liquid-cooled vapor condensers (see FIGS. 6A-9B)disposed within the systems) and node-to-manifold fluid connect hoses234 coupling the individual electronic systems 210 to system coolantreturn manifold 232. Each MCU 230 is in fluid communication with systemcoolant supply manifold 231 via a respective system coolant supply hose235, and each MCU 230 is in fluid communication with system coolantreturn manifold 232 via a respective system coolant return hose 236.

Heat load of the electronic systems 210 is transferred from the systemcoolant to cooler facility coolant within the MCUs 230 provided viafacility coolant supply line 240 and facility coolant return line 241disposed, in the illustrated embodiment, in the space between raisedfloor 145 and base floor 165.

FIG. 3 schematically illustrates one cooling approach using the coolingapparatus of FIG. 2, wherein a liquid-cooled cold plate 300 is showncoupled to an electronic component 301 of an electronic system 210within the liquid-cooled electronics rack 200. Heat is removed fromelectronic component 301 via system coolant circulating via pump 320through liquid-cooled cold plate 300 within the system coolant loopdefined, in part, by liquid-to-liquid heat exchanger 321 of modularcooling unit 230, hoses 235, 236 and cold plate 300. The system coolantloop and modular cooling unit are designed to provide coolant of acontrolled temperature and pressure, as well as controlled chemistry andcleanliness to the electronic systems. Furthermore, the system coolantis physically separate from the less controlled facility coolant inlines 240, 241, to which heat is ultimately transferred.

FIG. 4 depicts one detailed embodiment of a modular cooling unit 230. Asshown in FIG. 4, modular cooling unit 230 includes a facility coolantloop, wherein building chilled, facility coolant is provided (via lines240, 241) and passed through a control valve 420 driven by a motor 425.Valve 420 determines an amount of facility coolant to be passed throughheat exchanger 321, with a portion of the facility coolant possiblybeing returned directly via a bypass orifice 435. The modular coolingunit further includes a system coolant loop with a reservoir tank 440from which system coolant is pumped, either by pump 450 or pump 451,into liquid-to-liquid heat exchanger 321 for conditioning and outputthereof, as cooled system coolant to the electronics rack to be cooled.Each modular cooling unit is coupled to the system supply manifold andsystem return manifold of the liquid-cooled electronics rack via thesystem coolant supply hose 235 and system coolant return hose 236,respectively.

FIG. 5 depicts another cooling approach, illustrating one embodiment ofan electronic system 210 component layout wherein one or more air movingdevices 511 provide forced air flow 515 in normal operating mode to coolmultiple electronic components 512 within electronic system 210. Coolair is taken in through a front 531 and exhausted out a back 533 of thedrawer. The multiple components to be cooled include multiple processormodules to which liquid-cooled cold plates 520 are coupled, as well asmultiple arrays of memory modules 530 (e.g., dual in-line memory modules(DIMMs)) and multiple rows of memory support modules 532 (e.g., DIMMcontrol modules) to which air-cooled heat sinks may be coupled. In theembodiment illustrated, memory modules 530 and the memory supportmodules 532 are partially arrayed near front 531 of electronic system210, and partially arrayed near back 533 of electronic system 210. Also,in the embodiment of FIG. 5, memory modules 530 and the memory supportmodules 532 are cooled by air flow 515 across the electronics system.

The illustrated cooling apparatus further includes multiplecoolant-carrying tubes connected to and in fluid communication withliquid-cooled cold plates 520. The coolant-carrying tubes comprise setsof coolant-carrying tubes, with each set including (for example) acoolant supply tube 540, a bridge tube 541 and a coolant return tube542. In this example, each set of tubes provides liquid-coolant to aseries-connected pair of cold plates 520 (coupled to a pair of processormodules). Coolant flows into a first cold plate of each pair via thecoolant supply tube 540 and from the first cold plate to a second coldplate of the pair via bridge tube or line 541, which may or may not bethermally conductive. From the second cold plate of the pair, coolant isreturned through the respective coolant return tube 542.

As computing demands continue to increase, heat dissipation requirementsof electronic components, such as microprocessors and memory modules,are also rising. This has motivated the development of the applicationof single-phase, liquid-cooling solutions such as described above.Single-phase, liquid-cooling, however, has some issues. Sensible heatingof the liquid as it flows along the cooling channels and acrosscomponents connected in series results in a temperature gradient. Tomaintain a more uniform temperature across the heat-generatingcomponent, the temperature change in the liquid needs to be minimized.This requires the liquid to be pumped at higher flow rates, consumingmore pump power, and thus leading to a less efficient system. Further,it is becoming increasingly challenging to cool all the heat sources ona server or electronic system using pumped liquid, due to the densityand number of components, such as controller chips, I/O components andmemory modules. The small spaces and number of components to be cooledmake liquid plumbing a complex design and fabrication problem andsignificantly raises the overall cost of the cooling solution.

Immersion-cooling is one possible solution to these issues. Inimmersion-cooling, all components to be cooled are immersed in adielectric fluid that dissipates heat through boiling. The vapor is thencondensed by a secondary, rack-level working (or system) fluid usingnode or module-level, finned condensers, as explained below.

Direct immersion-cooling of electronic components of an electronicsystem of the rack unit using dielectric fluid (e.g., a liquiddielectric coolant) advantageously avoids forced air cooling and enablestotal liquid-cooling of the electronics rack within the data center.Although indirect liquid-cooling, such as described above in connectionwith FIGS. 3 and 5, has certain advantages due to the low cost and wideavailability of water as a coolant, as well as its superior thermal andhydraulic properties, where possible and viable, the use of dielectricfluid immersion-cooling may offer several unique benefits.

For example, the use of a dielectric fluid that condenses at atemperature above typical outdoor ambient air temperature would enabledata center cooling architectures which do not require energy intensiverefrigeration chillers. Yet other practical advantages, such as theability to ship a coolant filled electronic subsystem, may offer benefitover water-cooled approaches such as depicted in FIGS. 3 & 5, whichrequire shipping dry and the use of a fill and drain protocol to insureagainst freeze damage during transport. Also, the use of liquidimmersion-cooling may, in certain cases, allow for greater compaction ofelectronic components at the electronic subsystem level and/orelectronic rack level since conductive cooling structures might beeliminated. Unlike corrosion sensitive water-cooled systems, chemicallyinert dielectric coolant (employed with an immersion-cooling approachsuch as described herein) would not mandate copper as the primarythermally conductive wetted metal. Lower cost and lower mass aluminumstructures could replace copper structures wherever thermally viable,and the mixed wetted metal assemblies would not be vulnerable togalvanic corrosion, such as in the case of a water based coolingapproach. For at least these potential benefits, dielectric fluidimmersion-cooling of one or more electronic systems of an electronicsrack may offer significant energy efficiency and higher performancecooling benefits, compared with currently available hybrid air andindirect water cooled systems.

In the examples discussed below, the dielectric fluid may comprise anyone of a variety of commercially available dielectric coolants. Forexample, any of the Fluorinert™ or Novec™ fluids manufactured by 3MCorporation (e.g., FC-72, FC-86, HFE-7000, and HFE-7200) could beemployed. Alternatively, a refrigerant such as R-134a or R-245fa may beemployed if desired.

FIG. 6A is a schematic of one embodiment of a liquid-cooled electronicsrack, generally denoted 600, employing immersion-cooling of electronicsystems, in accordance with an aspect of the present invention. Asshown, liquid-cooled electronics rack 600 includes an electronics rack601 containing a plurality of electronic systems 610 disposed, in theillustrated embodiment, horizontally so as to be stacked within therack. By way of example, each electronic system 610 may be a server unitof a rack-mounted plurality of server units. In addition, eachelectronic system includes multiple electronic components to be cooled,which in one embodiment, comprise multiple different types of electroniccomponents having different heights and/or shapes within the electronicsystem.

The cooling apparatus is shown to include one or more modular coolingunits (MCU) 620 disposed, by way of example, in a lower portion ofelectronics rack 601. Each modular cooling unit 620 may be similar tothe modular cooling unit depicted in FIG. 4, and described above. Themodular cooling unit includes, for example, a liquid-to-liquid heatexchanger for extracting heat from coolant flowing through a systemcoolant loop 630 of the cooling apparatus and dissipating heat within afacility coolant loop 619, comprising a facility coolant supply line 621and a facility coolant return line 622. As one example, facility coolantsupply and return lines 621, 622 couple modular cooling unit 620 to adata center facility coolant supply and return (not shown). Modularcooling unit 620 further includes an appropriately sized reservoir, pumpand optional filter for moving liquid-coolant under pressure throughsystem coolant loop 630. In one embodiment, system coolant loop 630includes a coolant supply manifold 631 and a coolant return manifold632, which are coupled to modular cooling unit 620 via, for example,flexible hoses. The flexible hoses allow the supply and return manifoldsto be mounted within, for example, a door of the electronics rackhingedly mounted to the front or back of the electronics rack. In oneexample, coolant supply manifold 631 and coolant return manifold 632each comprise an elongated rigid tube vertically mounted to theelectronics rack 601 or to a door of the electronics rack.

In the embodiment illustrated, coolant supply manifold 631 and coolantreturn manifold 632 are in fluid communication with respective coolantinlets 635 and coolant outlets 636 of individual sealed housings 640containing the electronic systems 610. Fluid communication between themanifolds and the sealed housings is established, for example, viaappropriately sized, flexible hoses 633, 634. In one embodiment, eachcoolant inlet 635 and coolant outlet 636 of a sealed housing is coupledto a respective liquid-cooled vapor condenser 650 disposed within thesealed housing 640. Heat removed from the electronic system 610 via therespective liquid-cooled vapor condenser 650 is transferred from thesystem coolant via the coolant return manifold 632 and modular coolingunit 620 to facility coolant loop 619. In one example, coolant passingthrough system coolant loop 630, and hence, coolant passing through therespective liquid-cooled vapor condensers 650 is water.

Note that, in general, fluidic coupling between the electronicsubsystems and coolant manifolds, as well as between the manifolds andthe modular cooling unit(s) can be established using suitable hoses,hose barb fittings and quick disconnect couplers. In the exampleillustrated, the vertically-oriented coolant supply and return manifolds631, 632 each include ports which facilitate fluid connection of therespective coolant inlets and outlets 635, 636 of the housings(containing the electronic subsystems) to the manifolds via the flexiblehoses 633, 634. Respective quick connect couplings may be employed tocouple the flexible hoses to the coolant inlets and coolant outlets ofthe sealed housings to allow for, for example, removal of a housing andelectronic subsystem from the electronics rack. The quick connectcouplings may be any one of various types of commercial availablecouplings, such as those available from Colder Products Co. of St. Paul,Minn., USA or Parker Hannifin of Cleveland, Ohio, USA.

One or more hermetically sealed electrical connectors 648 may also beprovided in each sealed housing 640, for example, at a back surfacethereof, for docking into a corresponding electrical plane of theelectronics rack in order to provide electrical and network connections649 to the electronic system disposed within the sealed housing when theelectronic system is operatively positioned within the sealed housingand the sealed housing is operatively positioned within the electronicsrack.

As illustrated in FIG. 6B, electronic system 610 comprises a pluralityof electronic components 642, 643 of different height and type on asubstrate 641, and is shown within sealed housing 640 with the pluralityof electronic components 642, 643 immersed within a dielectric fluid645. Sealed housing 640 is configured to at least partially surround andform a sealed compartment about the electronic system with the pluralityof electronic components 642, 643 disposed within the sealedcompartment. In an operational state, dielectric fluid 645 pools in theliquid state at the bottom of the sealed compartment and is ofsufficient volume to submerge the electronic components 642, 643. Theelectronic components 642, 643 dissipate varying amounts of power, whichcause the dielectric fluid to boil, releasing dielectric fluid vapor,which rises to the upper portion of the sealed compartment of thehousing.

The upper portion of sealed housing 640 is shown in FIG. 6B to includeliquid-cooled vapor condenser 650. Liquid-cooled vapor condenser 650 isa thermally conductive structure which includes a liquid-cooled baseplate 652, and a plurality of thermally conductive condenser fins 651extending therefrom in the upper portion of the sealed compartment. Aplenum structure 654 comprises part of liquid-cooled base plate 652, andfacilitates passage of system coolant through one or more channels inthe liquid-cooled base plate 652. In operation, the dielectric fluidvapor contacts the cool surfaces of the thermally conductive condenserfins and condenses back to liquid phase, dropping downwards towards thebottom of the sealed compartment.

System coolant supplied to the coolant inlet of the housing passesthrough the liquid-cooled base plate of the liquid-cooled vaporcondenser and cools the solid material of the condenser such thatcondenser fin surfaces that are exposed within the sealed compartment tothe dielectric fluid vapor (or the dielectric fluid itself) are wellbelow saturation temperature of the vapor. Thus, vapor in contact withthe cooler condenser fin surfaces will reject heat to these surfaces andcondense back to liquid form. Based on operating conditions of theliquid-cooled vapor condenser 650, the condensed liquid may be close intemperature to the vapor temperature or could be sub-cooled to a muchlower temperature.

Advantageously, in immersion-cooling, all of the components to be cooledare immersed in the dielectric fluid. The system fluid can tolerate alarger temperature rise, while maintaining component temperatures, thusallowing a smaller flow rate, and higher inlet temperatures, improvingenergy efficiency of the resultant cooling apparatus. However, two-phaseimmersion-cooling enclosures may require a large volume of dielectricfluid to completely cover the variously configured components within thesystem, including (for example) dual in-line memory modules (DIMMs),graphics boards, solid state drives (SSDs), and processors with tallheat spreader fins attached. This need for a large amount of dielectricfluid increases both the weight and the cost of the cooling solution.Disclosed hereinbelow with reference to FIGS. 7A-10 are alternateembodiments of a cooling apparatus, wherein partial immersion-cooling isemployed in combination with a condensate redirect structure, whichpreferentially redirects condensate drip onto selected, non-immersedelectronic components or portions thereof of the electronic system.These non-immersed components may be taller electronic components thatare only partially immersed, or may even be electronic componentssuspended within the electronic system such that they are completelynon-immersed within the dielectric fluid. The cooling apparatuses andmethods disclosed herein facilitate partial immersion-cooling ofelectronic components of an electronic system, and therebyadvantageously reduce the amount of dielectric fluid required within thesystem compared with a full immersion-cooling approach described abovein connection with FIGS. 6A-6B.

By way of example, the cooling apparatus includes a housing at leastpartially surrounding and forming a compartment about multipleelectronic components to be cooled, and a fluid disposed within thecompartment. A first electronic component of the multiple electroniccomponents is at least partially non-immersed within the fluid, and asecond electronic component of the multiple electronic components is atleast partially non-immersed within the fluid, wherein the first andsecond electronic components are different types of electroniccomponents with different configurations. The cooling apparatus furtherincludes a vapor condenser comprising a vapor-condensing surfacedisposed at least partially in a vapor region of the compartment forcondensing fluid vapor, and a condensate redirect structure disposedwithin the compartment at least partially between the vapor condenserand the first and second electronic components. The condensate redirectstructure is differently configured over the first electronic componentcompared with over the second electronic component, and provides adifferent pattern of condensate drip over the first electronic componentcompared with over the second electronic component.

In certain embodiments, the condensate redirect structure of the coolingapparatus may comprise different patterns of condensate drip openingsover the first electronic component compared with over the secondelectronic component, or the condensate redirect structure may comprisedifferently configured condensate drip openings over the firstelectronic component compared with over the second electronic component.The first electronic component may be a higher-heat-generatingelectronic component than the second electronic component, and in thatcase, the condensate redirect structure facilitates greater condensatedrip over the first electronic component compared with over the secondelectronic component. Thus, the condensate redirect structure mayinclude, for instance, different patterns of condensate drip openingsover the first and second electronic components, or differentlyconfigured condensate drip openings over the first and second electroniccomponents, with the different pattern of condensate drip over the firstelectronic component compared with over the second electronic componentbeing correlated, at least in part, to the different configurations ofthe first electronic component and the second electronic component.

By way of detailed example, FIGS. 7A & 7B depict a first coolingapparatus embodiment wherein the condensate redirect structure comprisesa vapor-permeable, liquid-phobic material with a plurality of condensatedrip openings disposed in different, sloped regions of the structure.These condensate drip openings may be differently shaped openings thatfacilitate, at least in part, a desired pattern of condensate drippingonto differently configured electronic components to be cooled.

In an alternate embodiment, the condensate redirect structure of thecooling apparatus may comprise a mesh structure with multiple condensatedrip pans supported by the mesh structure. One embodiment of thisconfiguration is depicted in FIGS. 8A-8B. In this configuration, and byway of example, a first condensate drip pan of the multiple condensatedrip pans is configured to provide a first pattern of condensate driponto the first electronic component, and a second condensate drip pan ofthe multiple condensate drip pans is configured to provide a secondpattern of condensate drip onto the second electronic component, whereinthe first pattern of condensate drip and the second pattern ofcondensate drip are different patterns of condensate drip. Further,vapor condenser condensing surfaces may be physically and/or chemicallymodified to, for example, increase condensation and condensate drip overselected regions of the electronic system.

In another embodiment, the condensate redirect structure of the coolingapparatus may be suspended at an angle within the compartment tofacilitate the flow of condensate drops along the suspended condensateredirect structure. In this embodiment, the suspended condensateredirect structure includes a drip pan with a plurality of condensatedrip openings, wherein multiple condensate drip openings of theplurality of condensate drip openings are aligned over, for example, thefirst and second electronic components. In addition, in this embodiment,the vapor condenser may include one or more sloped, thermally conductivefins which facilitate movement of condensed coolant drops in a firstdirection for dripping onto the condensate redirect structure at a firstside or other desired region thereof. In combination with this, thecondensate redirect structure may be suspended at an angle to facilitatemovement of the condensed coolant drops in a second direction along thecondensate redirect structure, wherein the second direction is differentfrom the first direction. In one embodiment, the second direction isopposite to the first direction.

Advantageously, the condensate redirect structure of the coolingapparatus is a shaped, porous structure disposed between the vaporcondenser and the electronic components being cooled. The condensatedrip structure facilitates collecting condensed coolant drops, anddripping the condensate preferentially over, for example, the at leastpartially non-immersed electronic components of the electronic system,which may include DIMMs, graphics and network cards, solid state drives,heat-spreader extended surfaces, etc. The condensed coolant drips ontothese partially non-immersed electronic components, with most of thecoolant making its way back into the pool of dielectric fluid at thelower region of the compartment, and with some of the condensate dripcontacting the non-immersed portions of the electronic componentevaporating directly, and thus cooling the heated, non-immersedelectronic component, or portion thereof extending from the dielectricfluid. Thus, a smaller fill height of dielectric coolant is required,and less volume of dielectric coolant is needed in this partialimmersion-cooling implementation. This reduction in coolant fluid helpsto reduce the cost and weight of the immersion-cooling solution. Inaddition to this specific advantage, an immersion-cooling solution hasseveral inherent advantages, including improved temperature uniformityacross the various components, lower required flow rate of the systemcoolant, and potential for warm water-cooling. The latter advantageimproves energy efficiency, and may enable the use of economizers.

FIG. 7A is a cross-sectional elevational view of one embodiment of acooled electronic system, generally denoted 700, comprising a coolingapparatus in accordance with one or more aspects of the presentinvention. In one embodiment, the cooling apparatus may be configured toaccommodate an electronic system (or node) of an electronics rack, suchas described above in connection with FIGS. 6A & 6B. In such anembodiment, a rack-level inlet manifold and rack-level outlet manifoldwould facilitate distribution of system liquid coolant 711 through theliquid-cooled vapor condenser 710 of the cooling apparatuses associatedwith the electronic systems of the electronics rack (as describedfurther below in relation to the example of rack unit of FIG. 10).Further, depending upon the implementation, there may be a singlecooling apparatus for an electronic system cooling, for instance,substantially the entire electronic system or multiple such coolingapparatuses within the electronic system, for example, to separatelycool different electronic components thereof.

As illustrated in FIG. 7A, liquid-cooled vapor condenser 710 includes(in this example) a plurality of thermally conductive fins 712, whichcomprise one or more vapor-condensing surfaces disposed at leastpartially in a vapor region of a compartment 720 defined by a housing702 at least partially surrounding and forming compartment 720 aboutmultiple differently-sized electronic components 721, 722, 723, 724,etc., to be cooled. The vapor condenser, with the plurality of thermallyconductive condenser fins 712 facilitates condensing of fluid vaporrising to the upper region of compartment 720. Housing 702 is mounted,in this example, to a substrate 701, such as a printed circuit board, towhich the plurality of electronic components to be cooled are attached.Attachment mechanisms 705 (e.g., screws) and gasket seals 706 facilitateforming a fluid-tight compartment about the electronic components. Afluid 730, such as a dielectric fluid, only partially fills compartment720. By way of example, the fluid may fill less than 50% of thecompartment. Note that in the example of FIG. 7A, the multipledifferently-sized electronic components 721, 722, 723, 724, etc., may befully immersed, partially immersed, partially non-immersed, or fullynon-immersed, within the dielectric fluid. In one implementation, theseelectronic components may be different types of electronic components,with different configurations. A sealable fill port 703 may be providedwithin housing 702 to facilitate adding dielectric fluid to thecompartment.

In the example of FIG. 7A, the cooling apparatus further includes acondensate redirect structure 740, which in this embodiment, comprises avapor-permeable, liquid-phobic material 741. In one embodiment, thisliquid-phobic material may be formed as a laminate structure andcomprise, as illustrated in FIG. 7B, multiple sloped regions 742. Thesesloped regions angle inwards and downwards from adjoining interfaces 743between regions towards respective condensate drip openings 744 a, 744b, 744 c, 744 d, 744 e, & 744 f, which are differently configured inthis example. Advantageously, the condensate drip openings within thedifferent regions are configured and/or patterned to facilitatecondensate preferentially dripping onto underlying electronic componentsthat are non-immersed within the dielectric fluid 730. By way ofexample, electronic component 721 may comprise dual in-line memorymodules (DIMMs), which are cards upon which memory modules are affixed.These DIMMs are tall, thin elongate structures, and condensate dripopenings 744 a in condensate drip structure 740 are sized and configuredto correlate, at least in part, to the configuration of the underlyingelectronic component 721 to be cooled. Similarly, condensate dripopenings 744 b, 744 c, 744 d, 744 e, & 744 f are, in one embodiment,sized and configured to provide a desired pattern of condensate dripover the underlying, partially non-immersed electronic component(s) tobe cooled.

As noted, the condensate redirect structure facilitates increasingcondensate drip over certain regions, or more particularly, certaincomponents of the electronic system. The structure may be fabricated, inone embodiment, with a shaped, porous coolant-impermeable,vapor-permeable sheet material. The sheet material may be shaped intoslight cones, which terminate at the condensate drip openings (e.g.,holes, slots, etc.) over the taller (or suspended), at least partiallynon-immersed electronic components to be cooled to allow the condensatedripping from the vapor condenser to preferentially drip over thenon-immersed components. Advantageously, substantially all condensate isdirected (in this embodiment) where desired by the condensate redirectstructure.

The angled shaping of the vapor-permeable redirect surfaces shown inFIGS. 7A & 7B is exaggerated, with only a slight amount of shapingactually required in order for the condensate drops to flow along thecondensate redirect structure to the condensate drip openings. The sizesof the different sloped regions helps to control the distribution of thecondensate drip fluid, with hotter electronic components requiring alarger collection area so that a larger amount of condensate drip isprovided over those electronic components. The use of a porousvapor-permeable sheet material allows the fluid vapor rising from theheated components to flow through the sheet and reach the vaporcondenser disposed in the upper region of the compartment, but the sheetimpedes the passage of the condensate drops dripping back from thethermally conductive condenser fins. Thus, vapor can generally flowthrough the entire sheet material of the condensate redirect structure,but the condensed drops can only flow back through the condensate dripopenings provided within the material. By way of example the porousmaterial could comprise PTFE, nylon, polycarbonate, polypropylene, etc.Such materials are available as thin, flexible sheets, and the shapingof the sloped regions could be achieved through heat treatment oflaminated versions of these films, where the laminate provides thenecessary mechanical stiffness, or through suspension of the native filmon an appropriately shaped mesh structure, such as a metal mesh.

Also provided, by way of example only, are heaters 725 immersed withindielectric fluid 730 in the cooling apparatus embodiments depicted inFIGS. 7A-9B. In one implementation, heaters 725 may be provided adjacentto, for example, the one or more at least partially non-immersedelectronic components within the compartment in order to initiate morequickly vaporization of fluid, and thus, condensate dripping in theregion of the non-immersed electronic components. If employed, heaters725 could be cycled on for a short time upon initiation of operation ofthe electronic system to start the cooling cycle described herein.

FIGS. 8A-9B depict alternate embodiments of the cooling apparatusdescribed above in connection with FIGS. 7A & 7B. Configuration andoperation of these cooling apparatuses is similar to that describedabove in connection with FIGS. 7A & 7B, unless noted otherwise below.

Cooled electronic system 800 of FIGS. 8A & 8B includes a coolingapparatus comprising a liquid-cooled vapor condenser 810 with one ormore channels to facilitate flow of liquid coolant 811 therethrough.Vapor condenser 810 further includes, in this embodiment, differentpatterns of thermally conductive condenser fins 812, which define one ormore vapor-condensing surfaces disposed at least partially in a vaporregion of compartment 720 defined by housing 702 partially surroundingand forming compartment 720 about multiple differently-sized electroniccomponents 721, 722, 723, 724, etc., to be cooled. The vapor condenser810, with the plurality of patterns of thermally conductive condenserfins 812, facilitates condensing of vapor fluid rising to the upperregion of compartment 720. In one embodiment, the different patterns ofcondenser fins 812 comprise different physical configurations and/ornumbers of condenser fins, which provide different densities of surfaceareas that are aligned, in this embodiment, over respective drip pans842 of a condensate redirect structure 840. If desired, one or more ofthe fins in one or more selected fin patterns may also be chemicallymodified to increase condensate drip where needed.

As illustrated in FIGS. 8A & 8B, condensate redirect structure 840includes, in one embodiment, a mesh structure 841 with a plurality ofcondensate drip pans 842 a, 842 b, 842 c, 842 d, 842 e, & 842 f,supported by the mesh structure 841. The condensate drip pans 842 a-842f (in this example) may be of different sizes and configurations, asillustrated in FIG. 8B. One or more condensate drip openings 844 a-844f, respectively, are provided within condensate drip pans 842 a-842 f.These openings are configured and positioned to provide a desiredpattern of condensate drip onto the underlying at least partiallynon-immersed electronic component to be cooled. The configuration andnumber of condensate drip openings 844 a-844 f may correspond, in oneembodiment, to the underlying configuration of the at least partiallynon-immersed electronic component being cooled by the condensate drip.Accumulating of condensate drops within the condensate drip pans 842a-842 f is facilitated by the above-noted, different patterns ofthermally conductive condenser fins 812 of the vapor condenser.

As a specific example, a first condensate drip pan of the multiplecondensate drip pans may be configured to facilitate a first pattern ofcondensate drip onto a first electronic component (e.g., electroniccomponent 721), and a second condensate drip pan of the multiplecondensate drip pans may be configured to facilitate a second pattern ofcondensate drip onto a second electronic component (e.g., electroniccomponent 722) of the electronic system. In this example the firstpattern of condensate drip and the second pattern of condensate drip aredifferent patterns of condensate drip, as can be ascertained from thecondensate drip openings depicted in the respective condensate drip pansillustrated in the example of FIG. 8B. The different patterns ofthermally conductive condenser fins over the different condensate drippans further facilitates accumulation of condensate drip within therespective, differently-sized condensate drip pans. In this embodiment,mesh structure 841 advantageously facilitates rise of fluid vapor withinthe compartment, but any condensate drip outside of the condensate drippans will drop through mesh structure 841.

In one example, mesh structure 841 may be a metal mesh, and theindividual-shaped condensate drip pans may be suspended on the meshstructure. Vaporized coolant flows around the drip pans through the openareas to reach the condenser above. In this embodiment, it is beneficialto increase the density of the condenser fins, or more particularly, toincrease the condenser surface area and/or condenser tubing directlyover the condensate drip pans so as to increase the amount of condensatedrip into the pans. Condensate drops that form elsewhere simply dripback down into the coolant pool, without being directed towards the atleast partially non-immersed electronic components to be cooled.

Advantageously, the embodiment of FIGS. 8A & 8B is simpler andpotentially less expensive to manufacture than the embodiment describedabove in connection with FIGS. 7A & 7B, due to the use of standardmaterials for the mesh and drip pans. However, this embodiment doesemploy a modified vapor condenser to encourage preferential condensationdrops over certain regions of the board, and a certain amount of thecondensate drip will not be collected and preferentially dripped backtowards the at least partially non-immersed electronic components.

FIGS. 9A & 9B show another alternate embodiment of a cooled electronicsystem 900, comprising a cooling apparatus in accordance with one ormore aspects of the present invention. In this embodiment, the coolingapparatus includes a liquid-cooled vapor condenser 910 and a condensateredirect structure 940, which in one embodiment, may comprisespecially-configured drip pans (such as depicted in FIG. 9B). Condensateredirect structure 940 is suspended via suspension structures 941 sothat its upper surface 942 is angled or sloped from a first side 945 toa second side 946 of condensate redirect structure 940. As condensatemoves from the first side to the second side of the condensate redirectstructure, it drips through openings 943 provided in one or morechannels or condensate transport regions 942 of condensate redirectstructure 940. As in the above-described cooling apparatus embodiments,condensate drip is preferentially provided over one or more at leastpartially non-immersed electronic components of the electronic systembeing partially immersion-cooled. This is achieved by, in oneembodiment, configuring condensate redirect structure with a desiredpattern of channels or condensate transport regions 942, and condensatedrip openings 943 therein, so that the desired patterns of condensatedrip are achieved. Note that the embodiment depicted in FIG. 9B is oneembodiment only of this concept. Also, note that in this example,different numbers of condensate drip openings may be provided over thedifferently configured, at least partially non-immersed electroniccomponents to be cooled.

As illustrated in FIG. 9A, condensate collection and preferential dripis further facilitated by providing vapor condenser 910 with one or moresloped, thermally conductive fins 912 that facilitate movement ofcondensed coolant drops in a first direction 915 for dropping ontocondensate redirect structure 940 at first side 945 thereof, wherein thecondensate redirect structure 940 is suspended to facilitate movement ofthe condensate in a second direction 916 along the condensate redirectstructure. In the embodiment depicted, the second direction is differentfrom the first direction, and more particularly, is opposite to thefirst direction.

In the embodiment depicted in FIGS. 9A & 9B, condensate collected at,for example, first side 945, is redirected and dripped back onto the atleast partially non-immersed electronic components to be cooled. Thecondensate redirect structure may include or be fabricated as a drip panthat includes a plurality of connected channels such that condensatedrops collected at the first side of the structure flow along thedifferent channels or condensate transport regions, dripping over the atleast partially non-immersed electronic components to be cooled as theydo. The shape of the channels (or condensate transport regions), as wellas the shape and number of condensate drip openings and density,determine how much condensed coolant drips over particular partiallynon-immersed electronic components. The vapor condenser with the sloped,thermally conductive condenser fin(s) also encourages condensate dropsthat have condensed elsewhere to flow towards the first side ofcondensate redirect structure 940 for accumulating and dripping back, asdescribed above. A wettability gradient may also be applied, forexample, from the left side (liquid-phobic) to the right side(liquid-philic) to improve the flow of condensed liquid along thecondenser fin(s) towards the first side of the condensate redirectstructure.

Similar to the embodiment of FIGS. 8A & 8B described above, the solutionof FIGS. 9A & 9B is potentially easier to manufacture due to the use ofstandard materials, but requires the condenser to also be modified.Unlike the embodiment of FIGS. 7A & 7B, not all of the condensate willbe preferentially dripped back over the non-immersed electroniccomponents to be cooled. That is, a certain amount of the condensatedrops will return directly to the coolant pool without interacting withthe non-immersed components.

FIG. 10 depicts one embodiment of a liquid-cooled electronic system 1000comprising a liquid-cooled electronics rack 1001 with a plurality ofpartially immersion-cooled electronic systems 1010 disposed, in theillustrated embodiment, horizontally, so as to be stacked within therack. By way of example, each electronic system 1010 may be a serverunit of a rack-mounted plurality of server units. In addition, eachelectronic system may include multiple electronic components to becooled, which in one embodiment could comprise multiple different typesof electronic components having different heights and/or shapes withinthe electronic system.

By way of example, the cooling system comprises one or more coolingapparatuses such as described above in connection with FIGS. 7A-9B. Inparticular, each cooling apparatus 1015 surrounds and forms acompartment about multiple electronic components of the electronicsystem 1010 to be cooled, and a vapor condenser comprises aliquid-cooled structure with, in one embodiment, a serpentine coolantchannel 1017 passing therethrough. Fluid vapor rising to the upperregion of the compartment is condensed into condensate drops and fallsback onto the condensate redirect structure, such as described above inconnection with the embodiments of FIGS. 7A-9B. The cooling apparatusfurther includes one or more modular cooling units (MCUs) 1020 disposed,by way of example, in a lower portion of electronics rack 1001. Eachmodular cooling unit 1020 may be similar to the modular cooling unitdepicted in FIG. 4, and described above. The modular cooling unit 1020includes, for example, a liquid-to-liquid heat exchanger 1021 forextracting heat from system coolant flowing through a system coolantloop 1030 of the cooling apparatus, and dissipating heat within afacility coolant loop 1025, comprising a facility coolant supply lineand a facility coolant return line. As one example the facility coolantsupply and return lines couple modular cooling unit 1020 to a datacenter facility coolant supply and return (not shown). Modular coolingunit 1020 further includes an appropriately sized reservoir 1022, pump,and optional filter (not shown), for moving liquid coolant underpressure through system coolant loop 1030. In one embodiment, systemcoolant loop 1030 includes a coolant supply manifold 1031, and a coolantreturn manifold 1032, which facilitate flow of system coolant (e.g.,water) through, for example the liquid-cooled vapor condensers of thecooling apparatuses 1015 disposed to cool the electronic components ofthe electronic systems 1010.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprise” (andany form of comprise, such as “comprises” and “comprising”), “have” (andany form of have, such as “has” and “having”), “include” (and any formof include, such as “includes” and “including”), and “contain” (and anyform contain, such as “contains” and “containing”) are open-endedlinking verbs. As a result, a method or device that “comprises”, “has”,“includes” or “contains” one or more steps or elements possesses thoseone or more steps or elements, but is not limited to possessing onlythose one or more steps or elements. Likewise, a step of a method or anelement of a device that “comprises”, “has”, “includes” or “contains”one or more features possesses those one or more features, but is notlimited to possessing only those one or more features. Furthermore, adevice or structure that is configured in a certain way is configured inat least that way, but may also be configured in ways that are notlisted.

The corresponding structures, materials, acts, and equivalents of allmeans or step plus function elements in the claims below, if any, areintended to include any structure, material, or act for performing thefunction in combination with other claimed elements as specificallyclaimed. The description of the present invention has been presented forpurposes of illustration and description, but is not intended to beexhaustive or limited to the invention in the form disclosed. Manymodifications and variations will be apparent to those of ordinary skillin the art without departing from the scope and spirit of the invention.The embodiment was chosen and described in order to explain theprinciples of the invention and the practical application, and to enableothers of ordinary skill in the art to understand the invention throughvarious embodiments and the various modifications thereto which aredependent on the particular use contemplated.

What is claimed is:
 1. A cooling apparatus comprising: a housing atleast partially surrounding and forming a compartment about multipleelectronic components to be cooled; a fluid disposed within thecompartment, wherein a first electronic component of the multipleelectronic components is at least partially non-immersed within thefluid and a second electronic component of the multiple electroniccomponents is at least partially non-immersed within the fluid, thefirst electronic component and the second electronic component beingdifferent types of electronic components with different configurations;a vapor condenser comprising a vapor-condensing surface disposed atleast partially in a vapor region of the compartment for condensingfluid vapor; and a condensate redirect structure disposed within thecompartment at least partially between the vapor condenser and the firstand second electronic components, the condensate redirect structurebeing differently configured over the first electronic componentcompared with over the second electronic component, and providing adifferent pattern of condensate drip over the first electronic componentcompared with over the second electronic component.
 2. The coolingapparatus of claim 1, wherein the condensate redirect structurecomprises different patterns of condensate drip openings over the firstelectronic component compared with over the second electronic component.3. The cooling apparatus of claim 1, wherein the condensate redirectstructure comprises differently configured condensate drip openings overthe first electronic component compared with over the second electroniccomponent.
 4. The cooling apparatus of claim 1, wherein the firstelectronic component is a higher heat-generating electronic componentthan the second electronic component, and the condensate redirectstructure facilitates greater condensate drip over the first electroniccomponent than over the second electronic component.
 5. The coolingapparatus of claim 1, wherein the condensate redirect structurecomprises at least one of different patterns of condensate drip openingsover the first and second electronic components, or differentlyconfigured condensate drip openings over the first and second electroniccomponents, wherein the different pattern of condensate drip over thefirst electronic component compared with over the second electroniccomponent correlates, at least in part, to the different configurationsof the first electronic component and the second electronic component.6. The cooling apparatus of claim 1, wherein the condensate redirectstructure comprises a vapor-permeable, liquid-phobic material with aplurality of condensate drip openings disposed therein to, at least inpart, allow condensate drip over the first electronic component and overthe second electronic component.
 7. The cooling apparatus of claim 6,wherein the plurality of condensate drip openings comprise differentlyshaped openings facilitating, at least in part, condensate dripping ontothe differently configured first electronic component and secondelectronic component.
 8. The cooling apparatus of claim 7, wherein thevapor-permeable, liquid-phobic material comprises multiple differentlysloped regions, the multiple differently sloped regions ofvapor-permeable, liquid-phobic material including differently shapedopenings therein which facilitate, at least in part, condensate drippingonto the differently configured first electronic component and secondelectronic component.
 9. The cooling apparatus of claim 1, wherein thecondensate redirect structure comprises a mesh structure with multiplecondensate drip pans supported by the mesh structure, a first condensatedrip pan of the multiple condensate drip pans being configured tofacilitate a first pattern of condensate drip onto the first electroniccomponent, and a second condensate drip pan of the multiple condensatedrip pans being configured to facilitate a second pattern of condensatedrip onto the second electronic component, wherein the first pattern ofcondensate drip and the second pattern of condensate drip are differentpatterns of condensate drip.
 10. The cooling apparatus of claim 9,wherein the vapor condenser further comprises a first pattern ofthermally conductive condenser fins extending within the vapor region ofthe compartment over the first condensate drip pan, and a second patternof thermally conductive condenser fins extending within the vapor regionover the second condensate drip pan, wherein the first pattern ofthermally conductive condenser fins and the second pattern of thermallyconductive condenser fins comprise different numbers of thermallyconductive condenser fins arranged in different patterns.
 11. Thecooling apparatus of claim 1, wherein the condensate redirect structureis suspended at an angle within the compartment to facilitate the flowof condensate drops along the condensate redirect structure, and whereinthe condensate redirect structure comprises a plurality of condensatedrip openings, multiple condensate drip openings of which are alignedover the first and second electronic components.
 12. The coolingapparatus of claim 11, wherein the vapor condenser further comprises atleast one sloped, thermally conductive fin facilitating movement ofcondensed coolant drops in a first direction for dropping onto thecondensate redirect structure at a first side thereof, and wherein thecondensate redirect structure is suspended to facilitate movement of thecondensed coolant drops in a second direction along the condensateredirect structure, wherein the second direction is different from thefirst direction.
 13. A liquid-cooled electronic system comprising: anelectronic system comprising multiple electronic components to becooled; a cooling apparatus partially immersion-cooling the electronicsystem, the cooling apparatus comprising: a housing at least partiallysurrounding and forming a compartment about the multiple electroniccomponents of the electronic system to be cooled; a fluid disposedwithin the compartment, wherein a first electronic component of themultiple electronic components is at least partially non-immersed withinthe fluid, and a second electronic component of the multiple electroniccomponents is at least partially non-immersed within the fluid, thefirst electronic component and the second electronic component beingdifferent types of electronic components with different configurations;a vapor condenser comprising a vapor-condensing surface disposed atleast partially in a vapor region of the compartment for condensingfluid vapor; and a condensate redirect structure disposed within thecompartment at least partially between the vapor condenser and the firstand second electronic components, the condensate redirect structurebeing differently configured over the first electronic componentcompared with over the second electronic component, and providing adifferent pattern of condensate drip over the first electronic componentcompared with over the second electronic component.
 14. Theliquid-cooled electronic system of claim 13, wherein the condensateredirect structure of the cooling apparatus comprises different patternsof condensate drip openings over the first electronic component comparedwith over the second electronic component.
 15. The liquid-cooledelectronic system of claim 13, wherein the first electronic component isa higher-heat-generating component than the second electronic component,and the condensate redirect structure facilitates greater condensatedrip over the first electronic component compared with over the secondelectronic component.
 16. The liquid-cooled electronic system of claim13, wherein the condensate redirect structure of the cooling apparatuscomprises at least one of different patterns of condensate drip openingsover the first and second electronic components, or differentlyconfigured condensate drip openings over the first and second electroniccomponents, wherein the different pattern of condensate drip over thefirst electronic component compared with over the second electroniccomponent correlates, at least in part, to the different configurationsof the first electronic component and the second electronic component.17. The liquid-cooled electronic system of claim 13, wherein thecondensate redirect structure of the cooling apparatus comprises avapor-permeable, liquid-phobic material with a plurality of condensatedrip openings disposed therein to, at least in part, allow condensatedrip over the first electronic component and over the second electroniccomponent, and wherein the plurality of condensate drip openingscomprise differently shaped openings facilitating, at least in part,condensate dripping onto the differently configured first electroniccomponent and second electronic component.
 18. The liquid-cooledelectronic system of claim 13, wherein the condensate redirect structureof the cooling apparatus comprises a mesh structure with multiplecondensate drip pans supported by the mesh structure, a first condensatedrip pan of the multiple condensate drip pans being configured tofacilitate a first pattern of condensate drip onto the first electroniccomponent, and a second condensate drip pan of the multiple condensatedrip pans being configured to facilitate a second pattern of condensatedrip onto the second electronic component, wherein the first pattern ofcondensate drip and the second pattern of condensate drip are differentpatterns of condensate drip, and wherein the vapor condenser of thecooling apparatus further comprises a first pattern of thermallyconductive condenser fins extending within the vapor region of thecompartment over the first condensate drip pan, and a second pattern ofthermally conductive condenser fins extending within the vapor regionover the second condensate drip pan, wherein the first pattern ofthermally conductive condenser fins and the second pattern of thermallyconductive condenser fins comprise different numbers of thermallyconductive condenser fins arranged in different patterns.
 19. Theliquid-cooled electronic system of claim 13, wherein the condensateredirect structure of the cooling apparatus is suspended at an anglewithin the compartment to facilitate the flow of condensate drops alongthe condensate redirect structure, and wherein the condensate redirectstructure comprises a plurality of condensate drip openings, multiplecondensate drip openings of which are aligned over the first and secondelectronic components, and wherein the vapor condenser of the coolingapparatus further comprises at least one sloped, thermally conductivefin facilitating movement of condensed coolant drops in a firstdirection for dripping onto the condensate redirect structure at a firstside thereof, and wherein the condensate redirect structure is suspendedto facilitate movement of the condensed coolant drops in a seconddirection along the condensate redirect structure, wherein the seconddirection is different from the first direction.
 20. A method offacilitating cooling of an electronic system, the method comprising:providing a housing at least partially surrounding and forming acompartment about multiple electronic components of the electronicsystem; providing a fluid disposed within the compartment in contactwith one or more electronic components of the multiple electroniccomponents within the compartment, wherein a first electronic componentof the multiple electronic components is at least partially non-immersedwithin the fluid and a second electronic component of the multipleelectronic components is at least partially non-immersed within thefluid, the first electronic component and the second electroniccomponent being different types of electronic components with differentconfigurations; providing a vapor condenser comprising avapor-condensing surface disposed at least partially in a vapor regionof the compartment for condensing fluid vapor; and disposing acondensate redirect structure within the compartment at least partiallybetween the vapor condenser and the first and second electroniccomponents, the condensate redirect structure being differentlyconfigured over the first electronic component compared with over thesecond electronic component, and providing a different pattern ofcondensate drip over the first electronic component compared with overthe second electronic component.